Alloys



' Patented Jan. 12, 1937 NlTED STATES PATENT OFFICE ALLOYS N 0 Drawing.

Application April 12, 1934, Serial No. 720,280. Renewed July 1, 1936 8Claims.

My invention, which relates to stainless socalled white metal having acopper base, and has among its objects the production of alloys of thiskind which may be readily worked into sheets and other forms by usualmill processes, will be best understood from the following descriptionof several examples of the alloy compounded according to the invention,the scope of which latter will be more particularly pointed out in theappended claims.

Heretofore copper base alloys containing nickel and chromium have beenemployed in practice only for castings. For economic reasons it has beenimpractical to roll or otherwise mechanically work such prior alloys asthey are brittle, difiicult to work cold, and next to impossible to workhot.

Applicant has found that workable stainless copper base alloys can beproduced by compounding copper, nickel and chromium in properproportions particularly when suitable precautions are taken to securesolution of the chromium and to prevent deleterious secondary compounds.These alloys may be readily cold and hot rolled into sheets and may beotherwise attenuated while cold or hot by usual mill processes toproduce variousshapes.

The alloys, which may be compounded with or without zinc, preferablycontain iron for causing the chromium to enter into solution.Ordinarily, to secure satisfactory results, at least twice as much ironas chromium should be employed, the iron, however, not exceeding about15% of the alloy.

' The alloys also preferably contain manganese, which primarily acts asa deoxidizer and desulphurizer for the nickel, but to some extent actsto protect the chromium against oxidization. Also small amounts oftitanium, say from 0.05 to about 0.3%, may be added to the melt fordeoxidizingthe chromium but without retaining any substantial amount ofthe titanium in the resulting alloy. In general, to prevent oxidization,best results will be secured when the metals are melted under cover,preferably under a layer of sodium fluoride. Sulphur, it has been found,tends to form nickel sulphide which acts to interfere with theworkability of the alloy. In the absence of protecting the chromiumagainst oxidization the chromium when melted in or with cupronickel islikely to come off as slag or be distributed throughout the alloy in theform of an oxide. Manganese, however, has a greater aflinity for sulphurthan has nickel, and manganese sulphide has no deleterious eilect on theworkability of the alloy. Any excess of manganese present, within theranges of metals hereinafter stated, enters into solution and augmentsthe efi'ect of the nickel as a whitener of the alloy, and improves itsgeneral working properties.

Thus the manganese acts to insure good work ing properties of the alloy,and acts to insure against sulphurization of the nickel, while the iron,which is soluble in the cupro-nickel, acts to cause solution of thechromium in the cupronickel.

When desired, the tensile strength of the alloy may be increased andcontrolled by addition of small amounts of vanadium, say from traces upto 0.1%, this metal remaining in the alloy and 15 much improving itscold working properties and its ductility and elongation. When employed,the vanadium may be substituted for an equal part of the copper.

The amount of nickel may be varied to vary 0 I the color of the alloy.With a high nickel content of about 18% a bright, clear white metalcharacteristic of the color of stainless steel is secured. By decreasingthe nickel content to 10% and below, alloys of warmer tones areobtained, with a suggestion of a rose or pinkish tint underlying thewhite, which warmer tones are desirable for architectural work. Thenickel content should ordinarily not exceed approximately from 20 to25%, as above these values the alloy becomes increasingly difiicult towork. On the other hand, the nickel content should not ordinarily beless than approximately from 4 to 5%, as below these values the alloyloses its characteristic color and ceases to be stainless.

The copper content should be relatively high, and ordinarily not lessthan approximately 65% of the alloy, as with lower copper values thealloy becomes increasingly brittle and difficult to work. Further, thecopper content should not 40 ordinarily exceed approximately when zincand manganese both are employed, or ordinarily exceed approximately 93%when zinc is omitted.

Further, to secure the desirable properties of the alloy within theranges of other constituents 45 hereinafter mentioned, the sum of thecopper and nickel should not ordinarily be less than approximately 80%,or when zinc is present exceed approximately 95%, or in the absence ofzinc exceed approximately 97%.

It has been found that the amount of chromium ordinarily should notexceed approximately 4 to 5% as values in excess of this make the alloydifilcult to work, and ordinarily should not be less 55 thanapproximately 0.5% to insure that the alloy is stainless.

Although the relation between the amounts of chromium and copper doesnot appear to be susceptible of exact mathematical expression, it hasbeen found that very roughly these amounts vary inversely and linearlyrelative to each other, that and nickel constituting substantially thebalance is to say, as a general rule, to produce best results ,K thehigher amounts of chromium should be employed with the lower amounts ofcopper, and vice versa. i

The manganese, under ordinary conditions, i should not exceed about 5%of the alloy, lest; within the range of chromium above stated, it causethe alloy to become refractory and brittle. Ordinarily to secureappreciable effects by the use of manganese at least 0.25% thereofshould be present. Very roughly, the amount of man.- ganese added to themelt within the ranges of metals specified, to secure satisfactoryresults under ordinary conditions, should vary directly with the amountof chromium, and preferably roughly equal amounts of these metals shouldbe added to the melt, which ordinarily will result in a preponderance ofmanganese in the alloy due to some of the chromium coming off in theslag. Therefore ordinarily to secure satisfactory results the amount ofmanganese should not be less than the amount of chromium.

Zinc, which may be employed to facilitate the soundness of thepreliminary castings, may be in amount between 1 and 18%.

As a suitable method of compounding the above alloys, the copper andiron may be melted under a flux of sodium fluoride and the temperatureof the melt raised to about 2600 F. To this initial melt the nickel,manganese and chromium may then be added in the formof a master alloy.After the melt is perfectly fluid and homogeneous, and just before themelt is poured, the vanadium maybe added as a vanadium-copper alloy. Thezinc, if employed, may be added in the form of brass to the melt justbefore pouring. The titanium when employed may be incorporated in themaster alloy.

As an example of satisfactory alloys according to the invention I mayemploy 20.2% nickel, 1.3%

chromium, 6% iron, balance substantially all copper, or the same alloyswith 2.5% manganese, or 5% zinc, or both, substituted for part of thecopper. Very satisfactory alloys are also secured with the chromium upto about 4% and the iron up to about 8% with the balance copper, nickeland manganese, good examples of these alloys being those having up toabout 3% chromium I and up to about 6% iron.

It will be understood that small proportions of other metals than thoseherein mentioned may bev added to the alloy to give it specialcharacteristics when they do not to a material extent change thehereinbefore mentioned desirable physical and chemical properties of thealloy,

and also that wide deviations may be made from the embodiments of theinvention herein described without departing from the spirit of theinvention.

I claim: 1, Stainless so-called white metal capable of of the alloy inrespect to the other metals specifled.

2. The alloys according to claim 1 containing from a trace to 0.1%vanadium substituted for an equal part of the copper.

3. Stainless so-called white metal capable of being hot and cold rolledcontaining, approximately, 20.2% nickel, 1.3% chromium, 6% iron, 2.5%manganese, balance substantially all copper.

4. Stainless so-called white metal capable of being hot and cold workedcontaining, approximately, 65 to 93% copper and 4 to 25% nickel, the sumof the copper and nickel being between approximately 80 and 97%, 0.5 to5% chromium, 1.5 to 5% manganese, the amount of manganese being not lessthan the amount of chromium, and 1 to 15% iron, but at least twice asmuch iron as chromium, the copper and nickel constituting substantiallythe balance of the alloy in respect to the other metals specified.

5. Stainless so-called white metal capable of being hot and cold workedcontaining, approximately, 65 to 93% copper and 4 to 25% nickel, the sumof the copper and nickel being between approximately 83 and 97%, 0.5 to4% chromium, 2 to 8% iron, but at least twice as much iron as chromium,0.5 to 5% manganese, the copper and nickel constituting the balance ofthe alloy in respect to the other metals.

6. Stainless so-called white metal capable of being" hot and cold workedcontaining, approximately, 65 to 93% copper and 4 to 25% nickel,

. the sum of the copper and nickel being between approximately 83 and97%, 0.5 to 4% chromium, 2 to 8% iron, but at least twice as much ironas chromium, 0.5 to 5% manganese, the amount of manganese being not lessthan the amount of chromium, the copper and nickel constituting thebalance of the alloy in respect'to the other metals.

7. Stainless so-called white metal capable of being hot and cold workedcontaining, approximately, 65 to 93% copper and 4 to 25% nickel, the sumof the copper and nickel being between approximately 86 and 97%, 0.5 to3% chromium, 2 to 6% iron, but at leasttwice as much iron as chromium,0.5 to 5% manganese, the copper andv nickel constituting the balance ofthe alloy in respect to the other metals.

8. Stainless so-called white metal capable of being hot and cold workedcontaining, approximately, 65 to 93% copper and 4 to 25% nickel, the sumof the copper and nickel being between approximately 86 and 97%, 0.5 to3% chromium,

balance of the alloy in respect to the other metals.

3 RICHARD A. WILKINS.

